Mobile storage systems are widely used in libraries or other storage facilities to maximise storage space. Mobile storage systems generally consist of a number of upright mobile storage units including shelves, which can be moved independently along floor-embedded tracks to which they are each independently operatively connected. The storage units can be moved longitudinally along the rails, and aisles can be created between two consecutive spaced-apart storage units to enable a person to access the content of the storage units located on either side of the aisle. Movement of the storage units is accomplished for example by rotating a handle located at one extremity of the storage unit, outwardly of the aisle formed between two storage units. The handle is operatively connected to and can induce rotation of a driving shaft, which in turn is operatively coupled to a number of driving wheels engaged in the floor-embedded tracks. When the handle is rotated, the driving wheels are also rotated, and the storage unit is set in motion along the tracks.
A person located within an aisle cannot readily access the handle to stop the movement of the storage unit. Safety considerations thus make it highly desirable to provide each storage unit with a braking system which can be quickly accessed by a person located within an aisle between two storage units. Indeed, each storage unit, once loaded with articles, generally has a considerable weight (e.g. thousands of kilograms). Once set in motion along the tracks, the loaded storage unit could crush a person against an adjacent storage unit if this person stands in the aisle. Thus, if a person standing in an aisle finds that one (or both) of the storage units on either side of the aisle is moving dangerously towards him, he can trigger the braking system to instantly interrupt the displacement of the corresponding storage unit against him which might otherwise result in him getting crushed between the two adjacent storage units.